/Engine/Source/Runtime/Landscape/Classes/LandscapeProxy.h
Return the landscape guid, used to identify landscape proxies (and splines) that belong to the same landscape, even across world partitions. Also used as the world partition grid guid. This value may be modified when the landscape is instanced, to allow multiple instances of the same landscape to exist simultaneously. If you want the original (uninstanced) value, useGetOriginalLandscapeGuid().
virtual [FGuid](API\Runtime\Core\Misc\FGuid) GetLandscapeGuid() const